1. Field of the Invention
The instant invention relates generally to air vent valves and more specifically it relates to a combination automatic and manual bleed valve for a hot water heating system.
Hot water heating consists of the circulation of hot water from a central heater through pipes to radiators and back to the heater. A centrifugal circulating pump is the usual motive power. The entire system, boiler, pipes and radiators is full of water under slight pressure to avoid the formation of air at the usual operating temperature for radiators of 208.degree. F. Vents keep the system free of air.
2. Description of the Prior Art
Air must be eliminated from hot water heating systems or they will become air-bound and sluggish in flow. High point in the main pipe is vented by an automatic vent valve. Each radiator is vented at the top where the air collects by a manual or an automatic vent valve. Manual vent valves are purge cocks which must be opened to let out the air periodically during the heating season.